The invention relates to a method for controlling rock drilling, in which method holes are drilled in rock according to a predetermined drilling plan, which determines the length and position of each hole with respect to the other holes in the rock to be drilled in a three-dimensional coordinate system.
The invention also relates to a rock drilling apparatus for drilling holes in rock according to a predetermined drilling plan, the apparatus comprising drilling means for drilling holes in rock, and control means for positioning the drilling means at each hole to be drilled and correspondingly for drilling a hole automatically according to said drilling plan.
It is previously known to use different types of measuring devices for measuring the deviation of a drill hole. The operation of such measuring devices is usually based on a compass, gravitation, inertia or any combination thereof. This type of measuring devices have been used especially in oil drilling technology for checking the direction of a drill hole and also for locating a hole. A problem with these measuring devices has been that the measurement is slow and the devices are large. Therefore, it has not been possible to use measurement of drill hole deviation or the measurement data for controlling drilling in ground excavation during rock drilling, nor for controlling the charging occurring after the drilling. When holes are drilled in rock especially during the excavation of tunnels or blasting of the material to be excavated, the accuracy of the drilling has become more and more important. Especially when drilling long holes, it is rather common that a hole becomes curved and the actual end of the hole is located rather far from the intended end position. Accordingly, the breakage of material, the orientation of a tunnel and other factors take place uneconomically and they may cause additional work and costs.
What is essential for the final result of the blasting is that the deviation of the drill hole and especially the location of the ends of the holes and therefore the relation of the hole ends with respect to one another must be known as accurately as possible in order that the blasting could be implemented in a desired manner. The purpose of the present invention is to provide a method and an apparatus which enable effective, accurate and rapid implementation of measurements and which also make it possible to change a predrafted drilling plan during the drilling, if required.
The method according to the invention is characterized by measuring at least the actual location of the end of at least predetermined drill holes in the rock by inserting or lowering into the drill hole a measuring device, which indicates its current location with respect to the rock in the three-dimensional coordinate system, calculating the deviation of the end of the measured hole from the location of the end determined in the drilling plan, and changing the drilling plan according to the calculated deviation.
The rock drilling apparatus according to the invention is characterized in that it comprises a measuring device that can be inserted or lowered into a drill hole, and feeding means for inserting or lowering the measuring device into the drill hole and for pulling it out of the hole, and transferring means for transferring the measurement values measured by the measuring device to the control means.
The basic idea of the invention is that a measuring device is inserted into a drill hole in order to measure at least the location of the hole end with respect to the rock in a three-dimensional coordinate system so as to determine the position of the hole end compared to the original drilling plan and thus with respect to the other holes.
Another basic idea of the invention is that the measurement result of the measuring device can be used, if required, to change the drilling plan of one or several successive holes or even to drill extra holes. A preferred embodiment of the invention comprises a separate feeding device with which an inertia measuring device is inserted into a drill hole directly after the drilling so that a measurement result is obtained immediately before the drilling apparatus is moved to the drilling point of the next hole, and required changes can be made before the drilling is started. According to another preferred embodiment of the invention, the measuring device is placed at the end of a feed hose that does not bend while it is pushed, so that the measuring device can be inserted into the hole and pulled out of it easily by using suitable mechanical feeding means for feeding the hose into the hole and for pulling it therefrom. According to a third preferred embodiment of the invention, the measuring device is fed into the hole simultaneously with the drill bit and the measurement is thus carried out simultaneously with the drilling. According to a fourth preferred embodiment of the invention, the measuring device is an inertia measuring device, which is inserted into the drill hole at such a speed that a reliable measurement result is obtained. Thus, if the initial point of the drill hole is known, it is possible to measure reliably the location of the hole end and, if required, the shape and direction of the hole continuously along the entire length of the hole.
The invention has an advantage that it enables measuring, simply and rapidly, the final location of the end of a drilled hole and also the shape and position of the entire hole. If required, it is thus possible to change the drilling plan so that the holes can be located suitably with respect to one other for the blasting. Depending on the application, the end of the drill hole may refer to only the final end of the hole or to a predetermined length of the hole from the hole end towards the beginning thereof. The invention is easy to implement and automate, so that the operator does not have to make any special calculations, but an automatic control system attends to the operation of the apparatus automatically.